If your memory or mistyping leaves you without the right password to get into an account on a Linux computer, there's no need to reformat. Make Magazine's Hacks Blog gives a step-by-step account of the command line fix you can make by booting into "single user mode." The fix is written from an Ubuntu perspective, but applies to most any Linux system that boots with the GRUB manager. It's also a reminder that even a password-protected Linux box isn't truly protected from the curious, so consider encrypting your data or taking other measures. Photo by Carl Johan.